Disk holding device

ABSTRACT

A disk holding device according to the present invention is constituted by a turntable ( 21 ), a center hub ( 25 ), plural claw-shaped members ( 26 ), elastic members ( 27 ) which energize the claw-shaped members ( 26 ) in the direction of the radius of a disk ( 23 ), a centering ring ( 28 ) having an inclined portion ( 28   b ), which ring is movable in the direction vertical to the disk surface, and an elastic member ( 29 ) which energizes the centering ring ( 28 ) in the direction along which the disk ( 23 ) is pushed up. The internal diameter of the disk ( 23 ) engages with the inclined portion ( 28   a ) before a cylindrical portion of the internal diameter of the disk ( 23 ) gets over the claw-shaped members ( 26 ), whereby centering of the disk ( 23 ) is performed, and then the disk ( 23 ) is held. The disk holding device constructed as described above is able to hold an optical disk such as a CD, a DVD, or the like, and perform more reliable centering of the disk. In addition, the products can be slimed down, and further the number of parts and the amount of assembly work can be reduced.

TECHNICAL FIELD

The present invention relates to a disk holding device for holding adisk in an optical disk drive or the like.

BACKGROUND ART

In recent years, a compact, lightweight, and slim optical disk drive hasbeen increasingly developed so that the optical disk drive can becontained in a notebook type personal computer. With the development ofsuch optical disk drive, a disk holding device, which is slimed down byself-locking a disk on a turntable, has also been developed.

Japanese Published Patent Application No. Hei.10-188418 discloses aconventional disk holding device in which a disk holding mechanism and adisk centering mechanism are integrated into a turntable unit so that asingle spindle motor unit can hold every optical disk as well assimultaneously adjust the center position of the optical disk(hereinafter, referred to as centering). FIGS. 5 through 7 illustrate adisk holding device for holding a bonded disk (a DVD disk) which hasbeen recently developed. FIG. 5 is a cross-sectional view of the diskholding device in the state where the disk is not loaded. FIG. 6 is across-sectional view of the disk holding device in the state where thedisk is loaded. FIG. 7 is a top view of the disk holding device.

Hereinafter, the conventional disk holding device will be described withreference to the drawings.

A spindle motor 32 is mainly divided into a turntable unit 33 whichholds a disk 23 and a driving unit 37 which rotates the disk 23. Firstof all, claw-shaped members 26 which interfere with an edge of aninternal diameter portion of the disk 23 are provided in at least threepositions on the turn table 21 to hold the disk 23. Each claw-shapedmember 26 is pressed by an elastic member 27, and ribs 26 a on bothsides of each claw-shaped member 26 are supported by a straight guide(not shown) of a center hub 25. The driving unit 37 is a component whichmainly makes up a magnetic circuit, and it comprises a rotor yoke 34, amagnet 35, a coil 36, a base plate 39, a metal bearing unit 38 whichsupports a spindle shaft 24 forcibly inserted into the turntable 21, andthe like. The spindle shaft 24 slides on a thrust bearing 40. Further, aHall element 41 is disposed on a flexible printed circuit, FPC 42.

Next, holding of the conventional disk and the operation of a centeringring will be described.

When the disk 23 is loaded, the disk 23 is put on the turntable 21 whileslope portions 26 b of the claw-shaped members 26 arranged in at leastthree positions are being pressed down from above. At this time, eachclaw-shaped member 26 slides along a guide (not shown) in the center hub25 while giving a repulsive force to the elastic member 27, and hides inthe center hub 25. Further, an under-internal-diameter edge portion 23a, which is a lower edge portion of the internal diameter portion of thedisk 23, is engaged with an inclined portion 28 a of the centering ring28 just before the disk 23 adheres to a slip sheet 22 bonded on theturntable 21, and the disk 23 is held by the claw-shaped members 26arranged in at least three positions while being pressed by the elasticmembers 27 again. At this time, since a force always acts in thedirection in which the disk 23 is pushed up by three elastic members 29,the centering ring 28 can center the disk 23.

However, since, in this conventional structure, the centering ring 28 isarranged under the center hub 25, the timing at which the disk 23 isengaged with the inclined portion 28 a of the centering ring 28 and thetiming at which the disk 23 adheres to the slip sheet 22 bonded on theturntable 21 to be held by the claw-shaped members 26 are almostsimultaneous. Therefore, if the disk 23 is obliquely inserted, the edgeportion 23 a under the internal diameter of the disk 23 is not correctlyengaged with the inclined portion 28 a of the centering ring 28,resulting in deterioration of centering accuracy.

Further, in order to slim down the products, the elastic members 29 forpushing up the centering ring 28 must be arranged at every 120°, i.e.,in three positions, on the turntable 21, whereby the number of parts andthe amount of assembly work are increased, resulting in increased costsof the products.

The present invention is made to solve the above-described problems andhas for its object to provide a disk holding device which can slim downthe products, can perform holding and centering of a disk withreliability, and further can reduce the number of parts and the amountof assembly work.

DISCLOSURE OF THE INVENTION

A disk holding device according to one embodiment of the presentinvention comprises a turntable which is provided rotatably by a drivingmechanism; a center hub which generally engages with the internaldiameter of a disk provided on the turntable; plural claw-shaped memberswhich are contained in the center hub; elastic members which energizethe plural claw-shaped members in the direction of the radius of thedisk; a centering ring for adjusting the center position of the disk,which centering ring is positioned beneath the center hub and is movablein the direction vertical to the disk surface; an elastic member whichenergizes the centering ring in the direction along which the disk ispushed up; and an inclined portion which is provided in the centeringring and engages with the internal diameter of the disk; wherein theinclined portion is positioned on the periphery of the center hub, andengages with the internal diameter of the disk before a cylindricalportion of the internal diameter of the disk gets over the claw-shapedmembers.

According to the disk holding device constructed as described above,centering of the disk is performed before the disk is held on theturntable by the claw-shaped members, and thereafter the disk is held,whereby more accurate holding and centering of the disk can be realized.

According to the present invention, in the disk holding device asdiscussed above, the centering ring and the elastic member whichenergizes the centering ring in the direction along which the disk ispushed up are arranged in a space between a coil of the drivingmechanism which rotates the turntable, and a bearing metal unit whichsupports a spindle shaft forcibly inserted into the turntable.

According to the disk holding device constructed as described above,vertical strokes of the centering ring can be increased withoutincreasing the thickness of the products, and the inclined portion ofthe centering ring which centers the disk can be arranged on theperipheral side surface of the center hub, and further, the number ofparts can be reduced, thereby realizing cost reduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is across-sectional view of a disk holding device according to afirst embodiment of the present invention, in the state where no disk isloaded.

FIG. 2 is a cross-sectional view of the disk holding device according tothe first embodiment of the present invention, in the state where a diskis loaded.

FIG. 3 is a cross-sectional view of the disk holding device according tothe first embodiment of the present invention, in the state where a diskis being loaded.

FIG. 4 is a top view of the disk holding device according to the firstembodiment of the present invention.

FIG. 5 is a cross-sectional view of the conventional disk holding devicein the state where no disk is loaded.

FIG. 6 is a cross-sectional view of the conventional disk holding devicein the state where a disk is loaded.

FIG. 7 is a top view of the conventional disk holding device.

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1)

Hereinafter, a first embodiment of the present invention will bedescribed with reference to FIGS. 1 to 4.

FIG. 1 is a cross-sectional view of a disk holding device according tothe first embodiment of the present invention in the state where no diskis loaded. FIG. 2 is a cross-sectional view of the disk holding deviceaccording to the first embodiment of the present invention in the statewhere a disk is loaded. FIG. 3 is a cross-sectional view of the diskholding device according to the first embodiment of the presentinvention in the course of loading a disk. Further, FIG. 4 is a top viewof the disk holding device according to the first embodiment of thepresent invention.

In FIGS. 1 to 4, a turntable unit 33 comprises a disk centeringmechanism part 31 which centers a disk 23, a disk holding mechanism part30 which holds the disk 23, and a turntable 21. The disk centeringmechanism part 31 is positioned beneath the disk holding mechanism part30. An inclined portion 28 a of a centering ring 28 which engages withthe internal diameter of the disk 23 is positioned on the peripheralside surface of a center hub 25. Further, a driving unit 37 has aradial-gap-type structure as shown in FIGS. 1 and 2. The driving unit 37is a component which mainly makes up a magnetic circuit, and itcomprises a rotor yoke 34, a magnet 35, a coil 36, a base plate 39, ametal bearing unit 38 which supports a spindle shaft 24 forciblyinserted into the turntable 21, and the like. The spindle shaft 24slides on a thrust bearing 40. Further, a Hall element 41 is arranged onan FPC 42.

The disk centering mechanism part 31 is composed of the centering ring28 and an elastic member 29. The centering ring 28 is movable in thevertical direction to the disk surface. Further, the elastic member 29is guided on the peripheral side surface of a cylindrical portion 28 bof the centering ring 28 so that the centering ring 28 is alwaysenergized in the direction along which the disk 23 is pushed up, andpositional regulation of the disk 23 is performed in the center hub 25that generally engages with the internal diameter of the disk 23. Thecentering ring 28 and the elastic member 29 that energizes the centeringring 28 in the direction along which the disk is pushed up are arrangedby utilizing a space 43 between the coil 36 of the driving unit 37 andthe bearing metal bearing unit 38.

Further, the disk holding mechanism part 30 has a structure in whichclaw-shaped members 26 that engage with the internal diameter of thedisk 23 are arranged along the periphery of the center hub 25 at every120° in three positions. Each claw-shaped member 26 has bosses 26 a onboth sides. The bosses 26 a of the claw-shaped member 26 are engagedwith a guide groove which is provided in the center hub 25 but is notshown in the figure, whereby the claw-shaped member 26 is slidablysupported by the center hub 25 in the radial direction of the disk 23.The claw-shaped member 26 engages with an end of the elastic member 27contained in the center hub 25, and it is subjected to regulation in thevicinity of a center hub window 25 a while being pressed by the elasticmember 27. The bosses 26 a of the claw-shaped member 26 touch an endportion of a guide groove, which is not shown, of the center hub 25,thereby., performing this regulation. Preferably, a deformed ball madeof a resin, which is flattened into a claw shape, is employed as theclaw-shaped member 26. The other end of the elastic member 27 is fixedto the center hub 25 by a center hub boss 25 b. Preferably, acompression spring or the like can be employed as the elastic member 27.

This structure enables sliming-down of the disk holding mechanism. Aturntable protrusion 21 a is forcibly inserted into the internaldiameter portion of the center hub 25 having the disk holding mechanism.Further, a slip sheet 22 by which a slipping frictional torque of thedisk 23 is properly given is affixed within a range of a radius of 12˜14mm from the internal circumference side on the flat surface of theperipheral part of the turntable 21.

Next, the operation of the disk holding device according to the firstembodiment will be described. When the disk 23 is loaded on the diskholding device, as shown in FIG. 3, initially, anunder-internal-diameter edge portion 23 a, which is a lower edge portionof the internal diameter portion of the disk 23, engages with theinclined portion 28 a of the centering ring 28 arranged on theperipheral side surface of the center hub 25, and centering is performedbefore the disk 23 is held on the turntable 21 by the claw-shapedmembers 26. Thereafter, the disk 23 gets over the claw-shaped members26, adheres to the slip sheet 22 affixed on the turntable 21, and isheld on the turntable 21 by the claw-shaped members 26 pressed by theelastic members 27.

In the disk holding device according to the first embodiment, theinclined portion 28 a of the centering ring 28, which portion isprovided in the centering ring 2,8 that centers the disk, is positionedon the periphery of the center hub 25 and engages with the internaldiameter of the disk 23. Further, while the disk 23 is being loaded onthe turntable 21, the inclined portion 28 a of the centering ring 28engages with the internal diameter part of the disk 23, and thecentering ring 28 centers the disk 23. After centering the disk 23, thedisk 23 is held on the turntable 21. Therefore, the disk 23 isaccurately centered to be held on the turntable 21. Further, even whenthe internal diameter of the disk 23 varies, the inclined portion 28 acan absorb the variation in the internal diameter. Further, the numberof parts of the disk holding device can be reduced, thereby realizingcost reduction. Further, since the centering ring 28 and the elasticmember 29 are arranged by utilizing the space 43 between the coil 36 ofthe driving unit 37 and the bearing metal unit 38, also in the turntableunit 33 which is slimed-down, sufficient strokes can be ensured in thethrust direction which is necessary for the disk centering mechanismpart 31 without increasing the thickness of the turntable unit 33.

Industrial Availability

As described above, the disk holding device according to the presentinvention can realize accurate holding and centering of a disk. Inaddition, vertical strokes of the centering ring can be increasedwithout increasing the thickness of the products. Therefore, the numberof parts can be reduced, thereby realizing cost reduction. Especially,the disk holding device is effective in media that require highlyaccurate centering of optical disks such as a DVD-RAM, a DVD-ROM, andthe like.

What is claimed is:
 1. A disk holding device comprising: a turntablewhich is provided rotatably by a driving mechanism; a center huboperable to engage with an internal diameter of a disk provided on saidturntable; plural claw-shaped members contained in said center hub;elastic members operable to energize said plural claw-shaped members inthe direction of the radius of the disk; a centering ring operable toadjust a center position of the disk, said centering ring beingpositioned beneath said center hub and being movable in a directionnormal to the disk surface; an elastic member operable to energize saidcentering ring in the direction normal to the disk surface; and aninclined portion provided in said centering ring, said inclined portionbeing operable to engage with the internal diameter of the disk; whereinwhen the disk is not placed on said turntable, sliding of saidclaw-shaped members in the external disk diameter direction isrestricted by engaging a part of each of said claw-shaped members with acorresponding part of said center hub, and wherein said inclined portionis positioned on the periphery of said center hub and is operable toengage with the internal diameter of the disk before a cylindricalportion of the internal diameter of the disk gets over the claw-shapedmembers.
 2. A disk holding device as defined in claim 1, wherein saidcentering ring and said elastic member, which is operable to energizesaid centering ring in the direction normal to the disk surface, arearranged in a space between a coil of the driving mechanism whichrotates said turntable, and a metal bearing unit which supports aspindle shaft forcibly inserted into said turntable.
 3. A devicecomprising: a turntable; a driving mechanism operable to rotate saidturntable; a center hub operable to engage with an internal diameter ofa disk provided on said turntable; plural claw-shaped members containedin said center hub; elastic members operable to energize said pluralclaw-shaped members in the direction of the radius of the disk; acentering ring operable to adjust a center position of the disk, saidcentering ring being positioned beneath said center hub and beingmovable in a direction normal to the disk surface; an elastic memberoperable to energize said centering ring in the direction normal to thedisk surface; and an inclined portion provided in said centering ring,said inclined portion being operable to engage with the internaldiameter of the disk; wherein when the disk is not placed on saidturntable sliding of said claw-shaped members in the external diskdiameter direction is restricted by engaging a part of each of saidclaw-shaped members with a corresponding part of said center hub, andwherein said inclined portion is positioned on the periphery of saidcenter hub and is operable to engage with the internal diameter of thedisk before a cylindrical portion of the internal diameter of the diskgets over the claw-shaped members.
 4. A device as defined in claim 3,further comprising: a spindle shaft located at the center of saidturntable; and a metal bearing unit operable to support said spindleshaft; wherein said driving mechanism includes a coil, and wherein saidcentering ring and said elastic member, which is operable to energizesaid centering ring in the direction normal to the disk surface, arearranged in a space between said coil and said metal bearing unit.